1. Field of the Invention
This invention relates to flexible heaters which are suitable for heating seats in automobiles and other vehicles.
2. Introduction to the Invention
In cold climates, it is desirable to heat not only the air in the passenger compartment of an automobile or similar vehicle, but also the seats in which people are sitting. Until now, car seats have been heated, if at all, by means of series-connected heating wires. The known heaters, however, suffer from a variety of problems. These include failure due to intermittent flexing of the wires as the seat is occupied, the requirement for high power output to provide a minimum comfort level, the slow rate of heating due to the low ratio of heater coverage to seat area, and the partial penetration of the wires through the leather or fabric covering the seat leading to a "show through effect".
Attempts to correct some of these problems have been made. For example, Damron U.S. Pat. No. 3,781,526 discloses a sheet heater suitable for heating a stadium seat. The heater comprises an electrically conductive paper; interdigitated electrodes are positioned at the edges of the paper. Japanese Patent Publication No. 1-164,620/1989 (Toyoda Boshoku KK; Tokai Senko KK) discloses a durable, flexible sheet heater for heating vehicle seats. The heater comprises a fabric layer on which a conductive metal layer is electroplated. The resulting heater is attached to the seat cushion. Neither solution has solved all the problems.